1. Field of the Invention
The present invention relates to a display apparatus and a display driving method, and more particularly to a display apparatus and a display driving method suitable for driving a plasma display panel (PDP).
2. Description of the Related Art
With the recent trend toward larger-screen displays, the need for thin display apparatuses has been increasing, and various types of thin display apparatus have been commercially implemented. Examples include matrix panels that display images by directly using digital signals, such as PDPs and other gas discharge display panels, digital micromirror devices (DMDs), EL display devices, fluorescent display tubes, and liquid crystal display devices. Among such thin display devices, gas discharge display panels are considered to be the most promising candidate for large-area, direct-view HDTV (high-definition television) display devices, because of the simple production process which facilitates fabrication of larger-area displays, a self-luminescent property which ensures good display quality, and a high response speed.
A plasma display apparatus that utilizes a surface discharge has a structure such that a pair of electrodes are formed on the inner surface of a front glass substrate and a rare gas is filled therein. When a voltage is applied between the electrodes, a surface discharge occurs at the surface of a protective layer and a dielectric layer formed on the electrode surface, resulting in the emission of ultraviolet light. The inner surface of a rear glass substrate is coated with phosphors of three primary colors, red (R), green (G), and blue (B), which when excited by the ultraviolet light, produce visible light to achieve a color display.
In the plasma display apparatus, each field (frame) is divided into a plurality of weighted subfields (SFS: light emission blocks) each comprising a plurality of sustain discharge pulses (sustain pulses), and a gray scale display is achieved by combining these subfields. In a display apparatus that achieves a gray scale display by combining a plurality of such weighted subfields, a phenomenon can occur in which an unnatural color contour, which normally should not exist, appears on the surface of a moving image due to the persistence of human vision, etc. This phenomenon is generally known as “moving image false contour (or moving image pseudo contour.” In particular, when a person in a displayed image moves, a green or red color band occurs, for example, on the contour of the person's face or other flesh-colored portions, and this greatly degrades the picture quality.
In the prior art, techniques for improving the picture quality by reducing the moving image false contour phenomenon are proposed in Japanese Patent No. 3322809 (Japanese Unexamined Patent Publication (Kokai) No. 10-31455: JPP'455) and Japanese Unexamined Patent Publication (Kokai) No. 11-85101 (JPP'101). In the prior art, there is also proposed, in Japanese Patent No. 3357666 (Japanese Unexamined Patent Publication (Kokai) No. 2002-82649: JPP'649), a display apparatus and a display driving method in which, by using an error diffusion technique, the maximum gray scale level and the number of reproducible gray scale levels are made sufficiently large without increasing the number of subfields, while at the same time achieving enhancement in the reproducibility of low gray scale levels.
The prior art and its associated problems will be described later with reference to the accompanying drawings.